"Milking" is another one of those cloudy, undefined terms which can cause a lot of trouble with certain people. Some people say "milking" depends solely on frequency. Others say it depends on the effect frequency has on quality. And even others say it depends on if the game in question releases on a Nintendo console or not. And since it's not a formal term, you can't just pick a dictionary and claim its definition to be definitive over another definition. It's informal slang usually thrown around and its meaning is based on subjectivity for the most part.
That's why I say the word shouldn't be used at all in genuine discussion. Bringing up the term will likely ignite an unnecessary, heated argument over semantics. The discussion could be infinitely more smooth and clear by dishing the word "milk" and explicitly describing the game. Instead of saying "This game is milked", say "The frequency of installments for this series is too high for my tastes" or "the frequency of installments for this series has caused a drop in quality." That way you don't waste valuable time and bandwidth over semantics and spend more time analyzing the validity of arguments.







